On Wed, Sep 13, 2023 at 05:13:04PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
Thanks, applied to my next tree.
-corey
>
> In this case, strncpy is being used specifically for its NUL-padding
> behavior (and has been commented as such). Moreover, the destination
> string is not required to be NUL-terminated [2].
>
> We can use a more robust and less ambiguous interface in
> `memcpy_and_pad` which makes the code more readable and even eliminates
> the need for that comment.
>
> Let's also use `strnlen` instead of `strlen()` with an upper-bounds
> check as this is intrinsically a part of `strnlen`.
>
> Also included in this patch is a simple 1:1 change of `strncpy` to
> `strscpy` for ipmi_ssif.c. If NUL-padding is wanted here as well then we
> should opt again for `strscpy_pad`.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://lore.kernel.org/all/[email protected]/ [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Changes in v2:
> - use memcpy_and_pad (thanks Corey)
> - Link to v1: https://lore.kernel.org/r/20230912-strncpy-drivers-char-ipmi-ipmi-v1-1-cc43e0d1cae6@google.com
> ---
> drivers/char/ipmi/ipmi_msghandler.c | 11 +++--------
> drivers/char/ipmi/ipmi_ssif.c | 2 +-
> 2 files changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> index 186f1fee7534..d6f14279684d 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -5377,20 +5377,15 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
>
> j = 0;
> while (*p) {
> - int size = strlen(p);
> + int size = strnlen(p, 11);
>
> - if (size > 11)
> - size = 11;
> data[0] = 0;
> data[1] = 0;
> data[2] = 0xf0; /* OEM event without timestamp. */
> data[3] = intf->addrinfo[0].address;
> data[4] = j++; /* sequence # */
> - /*
> - * Always give 11 bytes, so strncpy will fill
> - * it with zeroes for me.
> - */
> - strncpy(data+5, p, 11);
> +
> + memcpy_and_pad(data+5, 11, p, size, '\0');
> p += size;
>
> ipmi_panic_request_and_wait(intf, &addr, &msg);
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 3b921c78ba08..edcb83765dce 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -1940,7 +1940,7 @@ static int new_ssif_client(int addr, char *adapter_name,
> }
> }
>
> - strncpy(addr_info->binfo.type, DEVICE_NAME,
> + strscpy(addr_info->binfo.type, DEVICE_NAME,
> sizeof(addr_info->binfo.type));
> addr_info->binfo.addr = addr;
> addr_info->binfo.platform_data = addr_info;
>
> ---
> base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> change-id: 20230912-strncpy-drivers-char-ipmi-ipmi-dda47b3773fd
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>